Yunus Yukselten

Hepatitis B virus (HBV) infection is a worldwide health concern that infects nearly 254 million people globally and causes more than 1 million deaths annually. The highest prevalence is seen in sub-Saharan Africa and the Western Pacific region. Cirrhosis, liver failure, and hepatocellular carcinoma (HCC) are reported as leading complications of chronic HBV. The route of transmission of this infection is mainly by exposure to infected blood and bodily fluids. Transmission from mother-to-child remains the predominant route in highly endemic areas. Vaccination has significantly reduced HBV seroprevalence and complications. However, incomplete vaccination of newborns continues to be a major obstacle to elimination of the disease. Current prevention strategies include universal vaccination, perinatal prophylaxis with hepatitis B immune globulin, and maternal antiviral therapy in pregnant women with high viral load. The management of chronic hepatitis B virus infection predominantly depends on nucleoside analogs, including entecavir, tenofovir disoproxil fumarate, and tenofovir alafenamide, as well as pegylated interferon alfa. These therapies effectively suppress viral replication and reduce the risks of cirrhosis, HCC, and liver-related mortality, but they rarely achieve functional cure characterized by hepatitis B surface antigen loss. The persistence of covalently closed circular DNA (cccDNA) remains a major hindrance in HBV eradication. Therefore, novel therapeutic strategies targeting different stages of the viral life cycle, including capsid assembly modulators, small interfering RNAs, nucleic acid polymers, and cccDNA-directed approaches, are under active investigation. This review summarizes the epidemiology, prevention, current therapies, clinical outcomes, and emerging therapeutic advances in HBV infection, highlighting ongoing efforts toward achieving a functional cure and global HBV elimination.

The C-C chemokine receptor type 5 (CCR5) is the principal co-receptor for R5-tropic HIV-1 and remains one of the most promising therapeutic targets in the pursuit of an HIV cure. The discovery that individuals carrying the naturally occurring CCR5Δ32 mutation exhibit marked resistance to HIV infection established the foundation for both genetic and pharmacological approaches to CCR5 inhibition. This review summarizes recent advances in CCR5-targeted therapies with a focus on CRISPR/Cas9-mediated gene editing and maraviroc-mediated receptor blockade. We discuss the molecular mechanisms, preclinical evidence and emerging clinical data supporting CRISPR-based CCR5 disruption, including multiplex editing strategies designed to overcome viral tropism switching. We also examine the evolving role of maraviroc beyond viral entry inhibition, highlighting its immunomodulatory effects, potential latency-reversing activity and applications in graft-versus-host disease and cancer. Together, these complementary strategies underscore the potential of CCR5-targeted interventions as integral components of future combination therapies aimed at achieving durable HIV remission or functional cure.

C-C chemokine receptor type 5 (CCR5) is the primary co-receptor mediating the entry of R5-tropic human immunodeficiency virus type 1 (HIV-1) into CD4+ T cells and macrophages, making it one of the most promising therapeutic targets in HIV cure research. The naturally occurring CCR5Δ32 mutation which abolishes surface CCR5 expression in homozygous individuals has provided strong clinical evidence for CCR5-directed strategies after multiple cases of sustained HIV remission following allogeneic hematopoietic stem cell transplantation (HSCT) from CCR5Δ32 donors. This review summarizes the current understanding of the evolutionary origin and global distribution of the CCR5Δ32 allele, as well as the clinical evidence from landmark transplantation cases. We also discuss recent findings demonstrating that durable HIV remission may be achieved following transplantation from heterozygous CCR5 wild-type/Δ32 donors, suggesting that factors such as donor chimerism, conditioning regimens and graft-versus-reservoir effects contribute substantially to reservoir clearance alongside CCR5 disruption. In addition, we examine emerging evidence that pharmacological inhibition of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway can reversibly suppress CCR5 expression, reduce HIV replication, limit reservoir establishment, and attenuate immune activation. Collectively, these advances highlight the evolving landscape of CCR5-targeted therapies and support the development of safer and more broadly applicable approaches toward durable HIV remission and, ultimately, an HIV cure.

Protein–protein interactions (PPIs) are fundamental to viral replication, regulating processes such as assembly, genome packaging, and virion maturation. Despite their biological importance, these interactions remain challenging to study and are relatively underexploited as therapeutic targets. Split reporter systems, based on protein-fragment complementation, provide quantitative platforms to measure PPIs by reconstituting reporter activity when interacting protein partners are brought into proximity. These systems can be applied in vitro and in live cells which enables detection of dynamic and multimeric interactions in physiologically relevant contexts. Major classes of split reporter systems include β-lactamase, alkaline phosphatase, luciferase-based platforms, green fluorescent protein, and horseradish peroxidase. Assay performance depends on factors such as fusion protein stability, expression levels, and reporter kinetics, which influence sensitivity, dynamic range, and reliability. These approaches have been applied to study viral protein interactions across diverse systems, including HIV-1 matrix and nucleocapsid proteins, flaviviral capsid proteins, hepatitis B virus core protein, and chikungunya virus capsid. Split reporter assays also enable high-throughput screening for small-molecule inhibitors that disrupt viral PPIs and multimerization. This provides a functional readout linked to viral replication. Despite the challenges that exist in assay optimization and protein stability, the sensitivity and versatility of these systems provide a framework to interrogate viral protein interactions and support the development of antiviral therapeutics.:

The aim of this study was to determine the appropriate doses of AT-101 and resveratrol combination in the in vitro hormone-refractory prostate cancer (PC) cell lines, in order to evaluate the cytotoxic and genotoxic effects of this combination on the proliferation of cancer cells, namely PC-3, DU-145 and LNCAP. Cytotoxicity in PC cell lines was analysed by using the XTT Cell Proliferation Assay. DNA damage was performed with the cell death assay. Apoptotic protein levels were performed by Roche Human Apoptosis Array. IC50 values were determined by XTT analysis. The strongest combined doses (100 µM resveratrol + 5µM AT-101) were found to have the strongest synergistic apoptotic and cytotoxic effects on DU-145 cells at 72 hr. While the combined use of resveratrol and AT-101 increased the expression of markers in apoptotic cell pathways on cells, a decrease in the expression of anti-apoptotic markers was detected (p ˂ 0.05). Combined applications of these compounds showed an important synergism in the hormone-refractory PC cell lines, and it was determined that after the post-translational modification, they were significantly effective on the apoptotic pathway. These results have revealed that the combination of resveratrol and AT-101 holds great expectation as a new chemotherapeutic application in the treatment of human prostate cancer.

This study examines the association of the −617 C > A polymorphism in the Nrf2 gene (rs6721961) with male infertility in a Turkish population and determines its functional role in spermatogenesis in correlation with the impact of different levels of DNA damage on the genotypes. A total of 100 infertile men and 100 healthy fertile men were included in the study. Nrf2 genotyping was performed with the PCR-based restriction fragment length gene polymorphism (RFLP-PCR) analysis. According to our results, the Nrf2 CC, CA, and AA genotype distribution frequencies were 58.6%, 38.4%, and 3% in the control group, respectively, and 38%, 48%, and 14% in the infertile men, respectively. The AA genotype was significantly higher in the patient group. In smokers, a significant difference was found in progressive motility values between the genotypes (p = 0.001). Also, sperm progressive motility and concentration decreased significantly in those smokers with the AA genotype; smokers carrying this genotype were also 5.75 times more likely to have oligoasthenozoospermia than those with CC (p < 0.05). There was a significant relationship between the number of cases with high sperm-DNA damage when comparing the frequency of Nrf2 AA genotype carriers with the CC genotype 16.3% vs. 6.9%, respectively (p < 0.001). These results suggest the importance of the Nrf2 gene C > A (rs 6,721,961) polymorphism in the etiology of sperm DNA damage as a risk factor for male infertility. Smokers carrying the AA genotype are more likely to impair seminal parameters through antioxidant mechanisms. Abbreviations: Polymerase chain reaction (PCR)-based restriction fragment length gene polymorphism (RFLP-PCR); reactive oxygen species (ROS); deoxyribonucleic acid (DNA); catalases (CATs); superoxide dismutase (SOD); glutathione peroxidase (GPX); glutathione-S-transferase (GST); Nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2); basic leucine zipper (bZIP); antioxidant response element (ARE); World Health Organization (WHO);normospermia(NS);asthenozoospermia(AS);oligozoospermia(OS);oligoasthenozoospermia (OAS); follicle stimulating hormone (FSH); ultraviolet (UV); low-melting-point agarose (LMA); normal-melting-point agarose (NMA); arbitrary units (AU); total comet score (TCS); A one-way analysis of variance (ANOVA); standard deviation (SD); N-acetyltransferase (NAT2); small non-coding RNAs (ncRNAs); microRNAs (miRNA)

Background/Aim:Multiple Myeloma (MM), characterized by aberrant accumulation of terminally differentiated plasma cells in the bone marrow, is promoted by ongoing DNA damage and genomic instability. O⁶-methylguanine-DNA-methyltransferase (MGMT), a DNA repair protein, transfers the alkyl group from guanine to its cysteine residue and is implicated as an important chemoresistance factor particularly in chemotherapy-induced DNA alkylation. A growing body of evidence has shown that enhanced DNA repair capacity stimulates cancer cell survival and facilitates genomic instability. Thus, targeting DNA repair activities including MGMT seems to be a promising strategy for the treatment of MM. Materials and Methods: In our study, MGMT expression was evaluated in MGUS, SMM and MM patients compared to normal plasma cells using publically available gene expression data sets (Gene Expression Omnibus; GSE47552). Furthermore, MGMT mRNA and protein levels were determined in human MM cell lines (NCI H929, RPMI 8226 and U266), three samples of control PBMCs, matched CD138+ myeloma and CD138- non-tumorigenic cells obtained from bone marrow aspirates of same MM patients [newly diagnosed (ND, n=12) and relapsed / refractory (RR, n=8)] by RealTime Ready PCR Assay and Western blot, respectively. The experiments with human cells were approved by the Ethical Committee of Ankara University School of Medicine. Following treatment of MM cells with Lomeguatrib for 48 hours, cell viability, cell cycle progression and apoptosis were assessed by MTT and flow cytometry. DNA damage levels were examined by alkaline comet assay and immunoblotting of ΥH2AX phosphorylation. Results: Comparable MGMT expression was detected between MM cells and normal plasma cells, and between ND CD138+ and RR CD138+ myeloma cells. Inhibition of MGMT activity by Lomeguatrib reduced MM cell viability and induced apoptosis in MGMT proficient but not in MGMT deficient MM cells in a dose-dependent manner. In contrast, Lomeguatrib did not affect the cell viability of PBMCs from three healthy donors and CD138- non-tumorigenic cells from three MM patients. Furthermore, Lomeguatrib perturbed cell cycle and decreased phosphorylation of G1/S specific CyclinE1 in these cells and led to an increase in DNA damage. Western blot analysis revealed a reduction in protein levels of Fen1, Ku-70 and Rad51 which are involved in double-strand DNA break repair. Conclusion: These results revealed that MGMT promotes repair of DNA double-strand breaks in MGMT proficient MM cells and MGMT inhibition enhances DNA damage-induced apoptosis, suggesting that inhibition of MGMT by Lomeguatrib might be a useful strategy to overcome unfaithful DNA repair in MM. This research has been supported by The Scientific and Technological Research Council of Turkey (No:113Z383).